The connection impedance to a transceiver of the type employed in so-called mobile telephones is often of the order of magnitude of 50 ohm. Depending, upon the design and type of radiator, its impedance may vary greatly, for example, within the range of between 100 and 1000 ohm. Thus, adaptation of the impedance is necessary.
In prior art designs and constructions, it is normal to build up an adaptation network of discrete components which are often placed on a circuit card in the communication device. Even if impedance adaptation in such designs and constructions may be satisfactory, these designs and constructions are generally expensive and suffer from high losses. Further, it is not possible, in this type of adaptation network, simply to include the antenna construction proper, as would be desirable since this would realise a simple and compact integral construction.
In mobile telephones in the stand-by mode, i.e. when the mobile telephone device is ready for receiving an incoming, signal, a small and compact antenna is further required, which, moreover must be mechanically durable and well protected. The degree of efficiency of such an antenna need not be sufficient to give complete range and transmission quality in the activated state, i.e. during talks. In order to realise a higher degree of efficiency in the antenna, use is often made of a retractable antenna ,which is employed in the activated state. Such a construction also presupposes the incorporation of an adaptation network between the antenna/antennas and the transceiver. There is a serious need in the art that all of these components can be downscaled to miniature and given good mechanical protection.